Validation of the Simplified Inguinal Pain Questionnaire for assessing postoperative pain and disability following hernioplasty.

The purpose of this study was to assess the psychometric properties of the Simplified Inguinal Pain Questionnaire (sIPQ) and compare it to the regular Inguinal Pain Questionnaire (IPQ) for external validation. To do so, the IPQ and sIPQ were telephonically administered at 7 and 28 days postoperatively for a cohort of 25 patients who underwent Lichtenstein hernioplasty. A psychometric analysis of the scores was done using Cronbach's alpha and test-retest assessments. The agreement rate of the mean-standardized values between scores was afterwards calculated. We found closely similar psychometric values for the IPQ and sIPQ. The agreement rate between scores was 97% (p < 0.001). Taken together, the results demonstrate that the sIPQ has psychometric values that are very similar to those of the full IPQ. Its shorter number of items is specifically designed to enable telephonic follow-up and streamline both postoperative care and telemedicine.

In a recent paper [1], using machine learning methods, our research team developed a simplified version of the Inguinal Pain Questionnaire (IPQ) by Fränneby et al. [2] This psychometric tool is designed to measure postoperative pain and disability following hernioplasty to identify those suffering from chronic pain. In the simplified version of the IPQ (sIPQ), we reduced the number of items from 18 to 8. This reduction was specifically designed to decrease the time required for its completion and enable telephonic follow-up of postoperative patients abided by the ongoing COVID-19 pandemic. While the psychometric properties of the sIPQ were found to be almost identical to those of the original IPQ in its developing cohort, no validation of the score was done. Therefore, in this study, we assess the sIPQ psychometric properties in an independent patient cohort.

Following Lichtenstein inguinal hernioplasty, 25 patients were enrolled in the study. Their characteristics are presented in Table 1. This sample size was calculated following the same steps and results of our previous study as well as the recommendation of a subject-to-item ratio ≥ 2 [1, 3]. The IPQ and sIPQ were telephonically administered at 7 days and 28 days postoperatively. The order in which the scores were administered was randomized to avoid bias. The time required to complete the IPQ was 13 IQR 5 min, compared to 7 IQR 3 min for the sIPQ (p < 0.001 in a paired Wilcoxon-rank sum test). Afterwards, we compared the full score values against those of the sIPQ (Table 2). Spearman’s rank correlation between the full IPQ and the sIPQ was 0.792, p < 0.001. Cronbach’s alpha for the IPQ data was 0.70 (95% CI 0.60–0.77), while for the sIPQ was 0.68 (95% CI 0.58–0.80). The score’s temporal stability was assessed by calculating the Spearman’s rank correlation of 7- and 28-day measurements. For the IPQ, its temporal stability was 0.68 (95% CI 0.52–0.82, p < 0.001) and for the sIPQ, 0.54 (95% CI 0.41–0.71, p < 0.001). Finally, to obtain the intraclass correlation coefficient (ICC) between the scores, we standardized them by subtracting the mean score value from each individual value and dividing the resulting number by the standard deviation. In that way, pairwise mean-standardized value comparisons were performed. The type 3–2 ICC between scores was 0.97 (95% CI 0.94–0.98) (Fig. 1).

Table 1

Patient characteristics

Variable	N = 25
Age	46.7 ± 13.5
Gender	Female = 5 (20%) Male = 15 (80%)
Hernia classification	NYHUS I = 6 (24%) NYHUS II = 7 (28%) NYHUS IIIa = 7 (28%) NYHUS IIIb = 5 (20%)
Inguinal pain questionnaire score	7-day PO = 22.3 ± 8.8 28-day PO = 17.7 ± 7.0
Simplified inguinal pain questionnaire score	7-day PO = 10.7 ± 4.7 28-day PO = 8.6 ± 3.5

Data are presented as the mean and standard deviation or proportions, as appropriate

Table 2

Simplified inguinal pain questionnaire

Item	Scoring
Estimate the pain you feel right now in the groin on the same side as the operation	0—No pain 1—Pain present but can easily be ignored 2—Pain present, cannot be ignored, but does not interfere with everyday activities 3—Pain present, cannot be ignored, interferes with concentration on chores and daily activities 4—Pain present, cannot be ignored, interferes with most activities 5—Pain present, cannot be ignored, necessitates bed rest 6—Pain present, cannot be ignored, prompt medical advice sought
Estimate the worst pain you felt in the operated groin during this past week	0—No pain 1—Pain present but can easily be ignored 2—Pain present, cannot be ignored, but does not interfere with everyday activities 3—Pain present, cannot be ignored, interferes with concentration on chores and daily activities 4—Pain present, cannot be ignored, interferes with most activities 5—Pain present, cannot be ignored, necessitates bed rest 6—Pain present, cannot be ignored, prompt medical advice sought
How often have you felt pain in the operated groin during the past week?	1—Once a week 2—2 to 5 times a week 3—Every day 4—Every day and also during nighttime 5—I have had pain the whole week, both at day and night
Do you find it difficult sitting down for more than half an hour because of the pain?	0—No 1—Yes
Do you find it difficult standing up for more than half an hour because of the pain?	0 – No 1 – Yes
Have you on any occasion taken painkillers for pain in the operated groin?	0—No 1—Yes
Estimate the severity of pain you feel right now in the groin opposite to the operated side	0—No pain 1—Pain present but can easily be ignored 2—Pain present, cannot be ignored, but does not interfere with everyday activities 3—Pain present, cannot be ignored, interferes with concentration on chores and daily activities 4—Pain present, cannot be ignored, interferes with most activities 5—Pain present, cannot be ignored, necessitates bed rest 6—Pain present, cannot be ignored, prompt medical advice sought
Estimate the worst pain you have felt in the groin opposite to the operated side during this past week	0—No pain 1—Pain present but can easily be ignored 2—Pain present, cannot be ignored, but does not interfere with everyday activities 3—Pain present, cannot be ignored, interferes with concentration on chores and daily activities 4—Pain present, cannot be ignored, interferes with most activities 5—Pain present, cannot be ignored, necessitates bed rest 6—Pain present, cannot be ignored, prompt medical advice sought

Fig. 1

Psychometric evaluation of the scores. The full value of the Inguinal Pain Questionnaire (IPQ) and its simplified version (sIPQ) were compared. Although there was a significant difference in their absolute values, the change slope between 7- and 28-day measurements is similar for the IPQ (a, blue) and the sIPQ (a, red). The correlation between the score absolute values was 79.2% (p < 0.001) (b), while the intraclass correlation coefficient for their mean-standardized values was 97.0% (p < 0.001) as shown in a Bland–Altman plot (c) and an expected vs. observed values plot (d). The shaded areas in the figure panels represent 95% CI

Taken together, our results demonstrate that the sIPQ has psychometric properties that are almost identical to those of the full IPQ, thereby adequately capturing pain and disability following hernioplasty. While other abbreviated forms of the IPQ exist [4], the sIPQ was developed using a rigorous statistical analysis in contrast to heuristically determining which items would be more clinically relevant. Furthermore, the sIPQ was also developed from patient’s data collected in the immediate and mediate postoperative period, rather than after several years after surgery. Some potential drawbacks of the sIPQ include the fact that it does not consider pre-operative pain (question 1 of the full IPQ), thus, failing to establish a pain baseline; and not considering other daily activities that may trigger pain and impact quality of life, except for sitting and standing. However, in our opinion, the most significant value that the sIPQ offers is enabling data collection in a consistent and abbreviated manner, thereby fostering its use for telemedicine. Consultations and surgical follow-up using virtual modalities during the COVID-19 pandemic has been found to be safe and effective and will likely be the norm for low-risk patients in the foreseeable future [5, 6]. Using validated, abbreviated, and refined tools can, therefore, make the data collection more efficient, allow for better telemedicine assessments, and the timely and correct identification of patients who may need in-person consultations.